Land Contamination: Technical Guidance on Special Sites: Acid Tar ...

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• benzole refining;• refining petroleum fractions, particularly in white oil production; and• oil re-refining.A brief outline of each of these processes is provided below.Benzole Refining Process• Benzole is a mixture of predominantly aromatic hydrocarbons that result from thewashing of residues from coal carbonisation processes with concentrated sulphuricacid to remove impurities, followed by distillation;• use of relatively untreated benzole in motor vehicle fuel declined in the 1960s andattempts were made at producing a more saleable product, including the use of moresevere acid treatment that produced a more acidic, thicker, more complex acid tar thanpreviously;• attempts to find new markets for benzole failed, however, and there are now very fewbenzole refineries in existence.White Oil Production Process• White oil is a liquid paraffin, frequently used in medicinal preparation, that is producedby removing unsaturated and aromatic hydrocarbons together with sulphur compoundsfrom heavy lubricant fractions;• the process involved a repetitive series of acid and alkali treatments (the acid being‘oleum’ - the most concentrated form of sulphuric acid) and the resulting acid tars weregenerally thicker, more acrid and more hazardous than those from benzole refining.Typically, Fuller’s Earth was used to absorb residual acid and is generally found codisposedwith acid tars;• sulphuric acid was also used in other petroleum fraction refining operations,particularly before 1930 when it was the only available process.Oil Re-refining Process (including oil refining)• Oil re-refining involved the removal of impurities such as lead, zinc and manganesefrom spent lubricating oils using concentrated sulphuric acid;• the acid tar resulting from this process was much more variable in composition thanthat from benzole refining and white oil production; its composition being dependenton a number of variables including the nature of the oil, the contaminants it containedand the amount of acid used.R&D <strong>Technical</strong> Report P5-042/TR/04 8
Overall CommentsAcid tars can be of very variable composition even from one type of process at one site. Thisis a function of variable process conditions and, in particular, the quantity and concentrationof acid used. Thus tars in one part of a lagoon may differ markedly from those in other partsof the lagoon - especially in terms of pH. The tar composition and quantities produceddepended on a number of variables including the type of coal/oil, carbonisation temperature(for benzole) and product required. Some generalisations can be made as set out in Box 2.1.Box 2.1 Comments on differences between tars from different types ofrefining• The thickest tars resulted from the use of small quantities of concentratedacids;• the thinnest tars resulted from the use of large quantities of weak acids.Benzole refining for motor benzole (pre-1960s)The aim was to purify the aromatics (BTX) without sulphonating themsignificantly since the latter would lead to inadvertent removal of the wantedaromatics. Therefore since process conditions must not be too severe, arelatively weak acid was used and the resulting tars were relatively thin.Purer benzole fractions (post-1960s)A more severe acid treatment using more concentrated acids was required andthe resulting tars were more viscous.White oil productionAromatics had to be removed which required ‘oleum’ (the most concentratedform of sulphuric acid) and the resultant tar was thicker, more acrid and morenoxious than that generally arising from benzole refining.Oil re-refiningThe volume and composition of the acid tar depended on the extent and type ofcontamination in the original oil, the contact time with the acid used and theprocess efficiency. Therefore a wide range of acid tars was produced.Acid tars that are produced currently in the UK are either incinerated or treated with alkalisprior to disposal in controlled landfill sites. In the past, producers frequently dumped themon-site (usually in a lagoon or void) in an uncontrolled manner. In some cases, this occurredover periods as long as 100 years, as various attempts to treat and utilise the tar were ofrelatively limited success.R&D <strong>Technical</strong> Report P5-042/TR/04 9
Page 1 and 2: Land Conta
Page 3 and 4: CONTENTSFOREWORDiGLOSSARYii1. Intro
Page 5 and 6: FOREWORDPart IIA of the Environment
Page 7 and 8: CresolsCreosoteDCRDesorptionDesulph
Page 9 and 10: PVCRCRASelosafeSodium saltsSodium h
Page 11 and 12: 1. INTRODUCTION1.1 BackgroundThis r
Page 13 and 14: SECTION 2: INDUSTRIAL PROCESS/FACIL
Page 15 and 16: 1.5 Linkages Between the Gu
Page 17: 2.1.2 Overview of acid tar lagoon s
Page 21 and 22: White Oil• Acid tar lagoons from
Page 23 and 24: Box 2.5 Scenario: Acid tar disposal
Page 25 and 26: 3. CHEMICAL AND PHYSICAL CHARACTERI
Page 27 and 28: Table 3.1 - General Physical Charac
Page 29 and 30: The chemicals listed in Table B.1,
Page 31 and 32: 4.2.3 Common mistakesIt is possible
Page 33 and 34: Geophysical methods, such as resist
Page 35 and 36: Investigation locations will need t
Page 37 and 38: • gas chromatography by simulatin
Page 39 and 40: 5.2.2 Water environmentThere is lit
Page 41 and 42: 5.3 Assessment of Investigation Dat
Page 43 and 44: 6. REMEDIATION ASPECTSKEY QUESTIONS
Page 45 and 46: 6.2.5 Solidification and stabilisat
Page 47 and 48: Box 6.1 Example of Remediation of A
Page 49 and 50: 6.3 Natural AttenuationNatural atte
Page 51 and 52: Table 6.1 - Remedial Options/Techni
Page 53 and 54: Table 6.2 - Remedial Options/Techni
Page 55 and 56: 6.4 ValidationThe principles of val
Page 57 and 58: • all personnel should follow a d
Page 59 and 60: Verschueren (1983) Handbook of Envi
Page 61 and 62: USEPA. Innovative Site Remediation

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